The width and interval of transverse centre line bars along the extended centre line of runway, in approach lighting system are A. 3 m and 30 m B. 4.2 m and 30 m C. 4.2 m and 50 m D. 3 m and 45 m

The correct answer is: A. 3 m and 30 m.

The transverse center line bars are located along the extended center line of the runway and are used to provide guidance to pilots during landing. The bars are 3 meters wide and are spaced 30 meters apart.

Option B is incorrect because the interval of the transverse center line bars is 30 meters, not 50 meters.

Option C is incorrect because the width of the transverse center line bars is 3 meters, not 4.2 meters.

Option D is incorrect because the interval of the transverse center line bars is 30 meters, not 45 meters.